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. Author manuscript; available in PMC: 2014 Aug 16.
Published in final edited form as: ACS Chem Biol. 2013 Jun 19;8(8):1704–1712. doi: 10.1021/cb300657r

Figure 1.

Figure 1

Cartoon of fluorogenic TMP-tag. Fluorogenic TMP-tag is based on the proximity-induced reaction between the E. coli dihydrofolate reductase (eDHFR) variant and the trimethoprim (TMP) – fluorophore (F) – quencher (Q) heterotrimer. The target protein (purple) is tagged with eDHFR (blue) and then labeled with TMP analogue. The high affinity interaction between TMP and eDHFR induces the SN2 reaction between a nucleophilic amino acid residue (Nu:) engineered on eDHFR and an electrophilic linker attached to the quencher as the leaving group.